Tap it.
I love red dots but be wary of looking for your training with it to carry over to your G17. With a dot, your shooting focus tends to be on the target with the dot projected over it. With iron sights, your focus is your front sight aligned with the target. I'm switching from dot to iron sights this week and the going through that struggle to maintain the right focus as I'm shooting. I agree using the dot will help you work on muscle memory while taking a break from worrying about the sights so much.